AD: Why study the gecko's sticking power?
KA: There's a big push to design smart adhesives that are sticky when and where you want them to be, but aren't sticky when you don't need them. We think the gecko has evolved the smartest adhesive of all. This is one that is made out of a very hard material that leaves no residue, attaches very strongly, but reverses very rapidly and with very little force to remove it.
AD: Where are scientists in terms of developing an actual gecko-like adhesive?
KA: We have just solved the big question of what makes geckos stick, and have proven that it's possible to make a synthetic version. But there's still a long way to go. Basic research questions still need to be answered. How do geckos control millions of hairs attaching and detaching in milliseconds? And how do geckos keep their feet clean, despite their adhesive traits? We're working on this right now in my lab.
AD: What are likely applications for an adhesive like this?
KA: Micromanipulation or pick-and-place applications in the microparts industry could help people handle delicate tiny objects, such as silicon chips, that you want to move from one place to another without getting it dirty or damaging it. Because the gecko hair is so fine, it can stick tight, leave no residue and detach without harming the material. Nanosurgery is another application in which you might want to pull on something, like a nerve or a blood vessel, but do so very gently.
AD: What are some possible consumer applications?
KA: Toys and sports equipment. You can imagine fumble-free gecko gloves or new kinds of climbing equipment. Your favorite football team could have gecko gloves and not drop the ball, or there could be safety devices for climbers. I can't watch the movie Spider-Man without thinking we should have Gecko Girl. My daughter Kendra has first dibs on being Gecko Girl. She's 6 years old and keeps asking me, â€œDad, where are my gecko gloves? Why aren't they done yet?â€?
AD: How long will it be before a prototype becomes available?
KA: About two years before we can make large, useful patches of our prototype.
AD: How would gecko adhesive improve upon existing adhesives?
KA: The reversibility is important: Adhesive based on gecko engineering would be sticky when you load it in one direction but not sticky when you load it in another. It works on a wide variety of materials â€” underwater, in a vacuum, sticking to pretty much anything except Teflon. And it can be made out of a wide variety of materials. This is like Velcro without the other side. It's like a magnet, but it can stick to nonferrous materials.
AD: How big a market could there be for gecko adhesives?
KA: It's huge. Think of Post-it Notes, Velcro and tape all put together. We'll see tape and Post-it Notes replaced by dry adhesives in 10 years. But what's really exciting to me is the use of this adhesive technology in novel places like microparts manipulation or aerospace. So astronauts may walk outside their spacecraft with gecko boots, like magnetic boots, except they'll walk on nonferrous materials. A personal dream of mine is to see a legged robot walk with gecko feet on Mars. In the future, firefighters or other rescue workers might toss a swarm of little gecko bots into a place that would be too dangerous for them to enter.
While vacationing in Hawaii six years ago, Kellar Autumn witnessed an event that would lead to his latest professional pursuit. Sitting in his hotel room one night, he looked up and saw a huge spider crawling across the ceiling. Then a little gecko approached, and a battle ensued. The lizard easily knocked the spider off the ceiling, prompting Autumn to wonder: What makes the gecko stick so well despite the pull of gravity?
The gecko's unsurpassed sticking power, which enables the lizard to support its weight with a single toe, had remained a mystery since it was first observed by Aristotle over two millennia ago. Autumn, an assistant professor of biology at Lewis & Clark College, ultimately led the team of scientists who unlocked the secret. His team discovered that van der Waals force helps the gecko's feet stick. This weak intermolecular bond, which scientists have known about for a while, occurs between any two materials that get very close.
â€œPutting a lot of small objects very close gives you a high force, and that's what geckos have evolved â€” a clever geometry, not a clever chemistry,â€? says Autumn, who currently has patents pending for a gecko-based adhesive. He recently spoke with American Demographics' Sandra Yin on the applications for synthetic adhesive based on nature's design.